Comparative Analysis of Free Space Optics and Single Mode Fiber

In this paper we have done comparative analysis of free space optics and single mode fibre optical channels system. Performance study is done for variable ranges 1km, 50km and 100km for the FSO and SMF channels. Single Mode Fiber and Free Space Optical Channel is observed that maximum Q factor, minimum bit error rate and signal power. FSO requires no licensing or frequency synchronization. It also provides the transmission of data with unlimited bandwidth. Results expose the ability of improving the Q factor by using these channels and the optimum effect concluded at (1km) length of optical rang by using the FSO channel i.e. the quality factor and signal power were increased to reach (1943 ) and (22.46dBm) respectively and MIN. BER is zero

Converging Cylindrical Shock Waves in a Nonideal Gas With an Axial Magnetic Field

This paper analyses the propagation of converging cylindrical shock waves in a nonidealgas, in the presence of an axial magnetic field. Chester-Chisnell-Whitham’s method has beenemployed to determine the shock velocity and the other flow-variables just behind the shockin the cases, when (i) the gas is weakly ionised before and behind the shock front, (ii) the gasis strongly ionised before and behind the shock front, and (iii) nonionised gas undergoes intenseionisation as a result of the passage of the shock. The effects of the nonidealness of the gas,the conductivity of the gas, and the axial magnetic field have been investigated. It is found thatin the case (i), an increase in the value of parameter ( ) characterising the nonidealness of thegas accelerates the convergence of the shock. In the case (ii), the shock speed and pressurebehind the shock increase very fast as the axis is approached; and this increase occurs earlierif the strength of the initial magnetic field is increased. In the case (iii), for smaller values of theinitial magnetic field, the shock speed, and pressure behind the shock decrease very fast afterattaining a maximum; and for higher values of the initial magnetic field, the tendency of decreaseappears from the beginning. This shows that the magnetic field has damping effect on the shockpropagation. In the case (iii), it was also found that the growth of the shock in the initial phaseand decay in the last phase were faster when it was converging in a nonideal gas in comparisonwith that in a perfect gas. Further, it has been shown that the gas-ionising nature of the shockhas damping effect on its convergence

Modeling Repulsive Gravity with Creation

There is a growing interest in the cosmologists for theories with negative energy scalar fields and creation, in order to model a repulsive gravity. The classical steady state cosmology proposed by Bondi, Gold and Hoyle in 1948, was the first such theory which used a negative kinetic energy creation field to invoke creation of matter. We emphasize that creation plays very crucial role in cosmology and provides a natural explanation to the various explosive phenomena occurring in local (z<0.1) and extra galactic universe. We exemplify this point of view by considering the resurrected version of this theory - the quasi-steady state theory, which tries to relate creation events directly to the large scale dynamics of the universe and supplies more natural explanations of the observed phenomena. Although the theory predicts a decelerating universe at the present era, it explains successfully the recent SNe Ia observations (which require an accelerating universe in the standard cosmology), as we show in this paper by performing a Bayesian analysis of the data.Comment: The paper uses an old SNeIa dataset. With the new improved data, for example the updated gold sample (Riess et al, astro-ph/0611572), the fit improves considerably (\chi^2/DoF=197/180 and a probability of goodness-of-fit=18%

Isothermal Shock Wave in Magnetogasdynamics

The problem of propagation of a plane isothermal discontinuity (shock) wave in a homogeneous semi-infinite body of a perfect gas, in the presence of amagnetic field have been solved. It has been shown that under certain definiteconditions, the density p at the wave front may be arbitrarily high for a singlecompression pulse. A certain class of solutions of the present problem for a nonhomogeneous semi-infinite body have been derived. Such solutions are expected to be of great importance in compression problems of plasma

On the Propagation of Shock Waves Produced by Explosion of a Spherical Charge in Deep Sea

The propagation of spherical shock waves, produced by explosion of a spherical charge in deep sea, have been studied using the, energy hypothesis of T.Y. Thomas. The energy release from the charge is supposed to be time dependent and the effects of earth's gravitation is taken into account. It is found that the shock compression varies very slowly with variation in the direction of shock propagation. The effects of earth's gravitation is to decrease the shock compression and its decay with shock radius. A comparison has also been made between the results of time dependent and instantaneous energy release

A study of the angular size-redshift relation for models in which Λ\Lambda decays as the energy density

By modifying the Chen and Wu ansatz, we have investigated some Friedmann models in which $\Lambda$ varies as $\rho$. In order to test the consistency of the models with observations, we study the angular size - redshift relation for 256 ultracompact radio sources selected by Jackson and Dodgson. The angular sizes of these sources were determined by using very long-baseline interferometry in order to avoid any evolutionary effects. The models fit the data very well and require an accelerating universe with a positive cosmological constant. Open, flat and closed models are almost equally probable, though the open model provides a comparatively better fit to the data. The models are found to have intermediate density and imply the existence of dark matter, though not as much as in the canonical Einstein-de Sitter model.Comment: LaTex, 15 pages including 2 figures (Revised version appeared in CQG

Genotypic correlation and path coefficient analysis for yield and yield contributing traits in released varieties of barley (Hordeum vulgare L.) under partially reclaimed saline sodic soil

This research sought to determine the correlations between grain yield and its contributing traits and to measure the direct and indirect effects on grain yield in barley. Sixty four released varieties were grown under par-tially reclaimed saline- sodic soil, under irrigated conditions during rabi 2010-11. The grain yield per plant showed highly significant and positive correlation with 1000 grain weight (0.517), plant height (0.460), length of main spike (0.459), fertile tillers per plant (0.385), and grains per main spike (0.366). On the basis of relationship of grain yield with yield contributing traits, we can select the best genotype and can be utilised in breeding program

Genetic variability and divergence analysis for yield and yield contributing traits in released varieties of barley (Hordeum vulgare L.) under partially reclaimed saline sodic soil

Genetic variability is the back bone of crop improvement programme, effectiveness of selection depends upon nature and magnitude of genetic variability present in the genetic material. The aim of the present study was that to identify the potential genotypes performing well under partially reclaimed saline- sodic soil (pH 8.6-8.9, EC = 4-4.2 dSm-1, ESP = &gt; 15). Sixty four released varieties of barley collected from Directorate of Wheat Research, Karnal were grown during rabi season 2010-11, showing wide spectrum of variation for various characters. The characters studied were yield and yield contributing traits; namely plant height, days to maturity, fertile tillers / plant, length of main spike, grains per main spike, 1000-grains weight, grain yield per plant. The data on 7 characters was utilized for estimation of mean, range and least significant differences. The varieties RD-2552(8.52), HBL-276(8.35), RD- 2592(8.17), PL-419(8.15), Kedar(8.11), PL-751(8.10), JB-58(8.06), K-508(7.96) produced higher grain yield per plant and showed high to very high mean performance for several other yield component also. These selected varieties can be used in breeding program and can be recommended direct cultivation under partially reclaimed salinesodic soil

Cosmological Models with Variable Gravitational and Cosmological constants in R2R^{2} Gravity

We consider the evolution of a flat Friedmann-Roberstson-Walker Universe in a higher derivative theories, including $\alpha R^{2}$ terms to the Einstein-Hilbert action in the presence of a variable gravitational and cosmological constants. We study here the evolution of the gravitational and cosmological constants in the presence of radiation and matter domination era of the universe. We present here new cosmological solutions which are physically interesting for model building.Comment: 14 pages, no figure. to be published in Int. J. Mod. Phys.